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Ferraboschi I, Ovčar J, Vygranenko KV, Yu S, Minervino A, Wrzosek A, Szewczyk A, Rozza R, Magistrato A, Belfield KD, Gryko DT, Grisanti L, Sissa C. Neutral rhodol-based dyes expressing localization in mitochondria. Org Biomol Chem 2024; 22:5886-5890. [PMID: 38804835 DOI: 10.1039/d4ob00252k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Neutral rhodol-based red emitters are shown to efficiently localize in mitochondria, as demonstrated by confocal microscopy and co-localization studies. A simple model is proposed to explain the localization mechanism of neutral molecules. The model takes into account the strong coupling between the molecular dipole moment and the electric field of the inner mitochondrial membrane.
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Affiliation(s)
- Ilaria Ferraboschi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy.
| | - Juraj Ovčar
- Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
- National Research Council - Materials Foundry Institute (CNR-IOM) c/o SISSA (International School for Advanced Studies), Via Bonomea 265, 34136 Trieste, Italy
| | - Kateryna V Vygranenko
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Shupei Yu
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - Alfonso Minervino
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - Antoni Wrzosek
- Nencki Institute of Experimental Biology of Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Adam Szewczyk
- Nencki Institute of Experimental Biology of Polish Academy of Sciences, Pasteura 3, 02-093 Warsaw, Poland
| | - Riccardo Rozza
- National Research Council - Materials Foundry Institute (CNR-IOM) c/o SISSA (International School for Advanced Studies), Via Bonomea 265, 34136 Trieste, Italy
| | - Alessandra Magistrato
- National Research Council - Materials Foundry Institute (CNR-IOM) c/o SISSA (International School for Advanced Studies), Via Bonomea 265, 34136 Trieste, Italy
| | - Kevin D Belfield
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - Daniel T Gryko
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Luca Grisanti
- Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
- National Research Council - Materials Foundry Institute (CNR-IOM) c/o SISSA (International School for Advanced Studies), Via Bonomea 265, 34136 Trieste, Italy
| | - Cristina Sissa
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy.
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2
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Kowaltowski AJ, Abdulkader F. How and when to measure mitochondrial inner membrane potentials. Biophys J 2024:S0006-3495(24)00176-0. [PMID: 38454598 DOI: 10.1016/j.bpj.2024.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 02/21/2024] [Accepted: 03/05/2024] [Indexed: 03/09/2024] Open
Abstract
The scientific literature on mitochondria has increased significantly over the years due to findings that these organelles have widespread roles in the onset and progression of pathological conditions such as metabolic disorders, neurodegenerative and cardiovascular diseases, inflammation, and cancer. Researchers have extensively explored how mitochondrial properties and functions are modified in different models, often using fluorescent inner mitochondrial membrane potential (ΔΨm) probes to assess functional mitochondrial aspects such as protonmotive force and oxidative phosphorylation. This review provides an overview of existing techniques to measure ΔpH and ΔΨm, highlighting their advantages, limitations, and applications. It discusses drawbacks of ΔΨm probes, especially when used without calibration, and conditions where alternative methods should replace ΔΨm measurements for the benefit of the specific scientific objectives entailed. Studies investigating mitochondria and their vast biological roles would be significantly advanced by the understanding of the correct applications as well as limitations of protonmotive force measurements and use of fluorescent ΔΨm probes, adopting more precise, artifact-free, sensitive, and quantitative measurements of mitochondrial functionality.
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Affiliation(s)
- Alicia J Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
| | - Fernando Abdulkader
- Departmento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
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3
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Nesci S. Proton leak through the UCPs and ANT carriers and beyond: A breath for the electron transport chain. Biochimie 2023; 214:77-85. [PMID: 37336388 DOI: 10.1016/j.biochi.2023.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 06/16/2023] [Indexed: 06/21/2023]
Abstract
Mitochondria produce heat as a result of an ineffective H+ cycling of mitochondria respiration across the inner mitochondrial membrane (IMM). This event present in all mitochondria, known as proton leak, can decrease protonmotive force (Δp) and restore mitochondrial respiration by partially uncoupling the substrate oxidation from the ADP phosphorylation. During impaired conditions of ATP generation with F1FO-ATPase, the Δp increases and IMM is hyperpolarized. In this bioenergetic state, the respiratory complexes support H+ transport until the membrane potential stops the H+ pump activity. Consequently, the electron transfer is stalled and the reduced form of electron carriers of the respiratory chain can generate O2∙¯ triggering the cascade of ROS formation and oxidative stress. The physiological function to attenuate the production of O2∙¯ by Δp dissipation can be attributed to the proton leak supported by the translocases of IMM.
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Affiliation(s)
- Salvatore Nesci
- Department of Veterinary Medical Sciences, University of Bologna, Ozzano Emilia, 40064, BO, Italy.
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4
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Kratochvil HT, Watkins LC, Mravic M, Thomaston JL, Nicoludis JM, Somberg NH, Liu L, Hong M, Voth GA, DeGrado WF. Transient water wires mediate selective proton transport in designed channel proteins. Nat Chem 2023; 15:1012-1021. [PMID: 37308712 PMCID: PMC10475958 DOI: 10.1038/s41557-023-01210-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 04/19/2023] [Indexed: 06/14/2023]
Abstract
Selective proton transport through proteins is essential for forming and using proton gradients in cells. Protons are conducted along hydrogen-bonded 'wires' of water molecules and polar side chains, which, somewhat surprisingly, are often interrupted by dry apolar stretches in the conduction pathways, inferred from static protein structures. Here we hypothesize that protons are conducted through such dry spots by forming transient water wires, often highly correlated with the presence of the excess protons in the water wire. To test this hypothesis, we performed molecular dynamics simulations to design transmembrane channels with stable water pockets interspersed by apolar segments capable of forming flickering water wires. The minimalist designed channels conduct protons at rates similar to viral proton channels, and they are at least 106-fold more selective for H+ over Na+. These studies inform the mechanisms of biological proton conduction and the principles for engineering proton-conductive materials.
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Affiliation(s)
- Huong T Kratochvil
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA.
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Laura C Watkins
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics and James Franck Institute, The University of Chicago, Chicago, IL, USA
- Kemper Insurance, Chicago, IL, USA
| | - Marco Mravic
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA
- Department of Integrative Structural and Computational Biology Scripps Research Institute, La Jolla, CA, USA
| | - Jessica L Thomaston
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA
| | - John M Nicoludis
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA
- Genentech, San Francisco, CA, USA
| | - Noah H Somberg
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics and James Franck Institute, The University of Chicago, Chicago, IL, USA.
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA.
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5
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Onukwufor JO, Dirksen RT, Wojtovich AP. Iron Dysregulation in Mitochondrial Dysfunction and Alzheimer’s Disease. Antioxidants (Basel) 2022; 11:antiox11040692. [PMID: 35453377 PMCID: PMC9027385 DOI: 10.3390/antiox11040692] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/21/2022] [Accepted: 03/28/2022] [Indexed: 02/04/2023] Open
Abstract
Alzheimer’s disease (AD) is a devastating progressive neurodegenerative disease characterized by neuronal dysfunction, and decreased memory and cognitive function. Iron is critical for neuronal activity, neurotransmitter biosynthesis, and energy homeostasis. Iron accumulation occurs in AD and results in neuronal dysfunction through activation of multifactorial mechanisms. Mitochondria generate energy and iron is a key co-factor required for: (1) ATP production by the electron transport chain, (2) heme protein biosynthesis and (3) iron-sulfur cluster formation. Disruptions in iron homeostasis result in mitochondrial dysfunction and energetic failure. Ferroptosis, a non-apoptotic iron-dependent form of cell death mediated by uncontrolled accumulation of reactive oxygen species and lipid peroxidation, is associated with AD and other neurodegenerative diseases. AD pathogenesis is complex with multiple diverse interacting players including Aβ-plaque formation, phosphorylated tau, and redox stress. Unfortunately, clinical trials in AD based on targeting these canonical hallmarks have been largely unsuccessful. Here, we review evidence linking iron dysregulation to AD and the potential for targeting ferroptosis as a therapeutic intervention for AD.
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Affiliation(s)
- John O. Onukwufor
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA; (R.T.D.); (A.P.W.)
- Correspondence:
| | - Robert T. Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA; (R.T.D.); (A.P.W.)
| | - Andrew P. Wojtovich
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA; (R.T.D.); (A.P.W.)
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
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6
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Jiang K, Mondal AK, Adlakha YK, Gumerson J, Aponte A, Gieser L, Kim JW, Boleda A, Brooks MJ, Nellissery J, Fox DA, Balaban R, Covian R, Swaroop A. Multiomics analyses reveal early metabolic imbalance and mitochondrial stress in neonatal photoreceptors leading to cell death in Pde6brd1/rd1 mouse model of retinal degeneration. Hum Mol Genet 2022; 31:2137-2154. [PMID: 35075486 PMCID: PMC9618164 DOI: 10.1093/hmg/ddac013] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 12/17/2021] [Accepted: 01/10/2022] [Indexed: 01/26/2023] Open
Abstract
Retinal diseases exhibit extensive genetic heterogeneity and complex etiology with varying onset and severity. Mutations in over 200 genes can lead to photoreceptor dysfunction and/or cell death in retinal neurodegeneration. To deduce molecular pathways that initiate and/or drive cell death, we adopted a temporal multiomics approach and examined molecular and cellular events in newborn and developing photoreceptors before the onset of degeneration in a widely-used Pde6brd1/rd1 (rd1) mouse, a model of autosomal recessive retinitis pigmentosa caused by PDE6B mutations. Transcriptome profiling of neonatal and developing rods from the rd1 retina revealed early downregulation of genes associated with anabolic pathways and energy metabolism. Quantitative proteomics of rd1 retina showed early changes in calcium signaling and oxidative phosphorylation, with specific partial bypass of complex I electron transfer, which precede the onset of cell death. Concurrently, we detected alterations in central carbon metabolism, including dysregulation of components associated with glycolysis, pentose phosphate and purine biosynthesis. Ex vivo assays of oxygen consumption and transmission electron microscopy validated early and progressive mitochondrial stress and abnormalities in mitochondrial structure and function of rd1 rods. These data uncover mitochondrial overactivation and related metabolic alterations as determinants of early pathology and implicate aberrant calcium signaling as an initiator of higher mitochondrial stress. Our studies thus provide a mechanistic framework with mitochondrial damage and metabolic disruptions as early drivers of photoreceptor cell death in retinal degeneration.
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Affiliation(s)
| | | | - Yogita K Adlakha
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA,Translational Health Science and Technology Institute, National Capital Region Biotech Cluster, Faridabad, India
| | - Jessica Gumerson
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA
| | - Angel Aponte
- Proteomics Core Facility, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Linn Gieser
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA
| | - Jung-Woong Kim
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA,Department of Life Science, College of Natural Sciences, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Alexis Boleda
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA,Center for Bioinformatics and Computational Biology, University of Maryland, College Park, MD 20740, USA
| | - Matthew J Brooks
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA
| | - Jacob Nellissery
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA
| | - Donald A Fox
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892, USA
| | - Robert Balaban
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Raul Covian
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Anand Swaroop
- To whom correspondence should be addressed. Tel: +301-435-5754; Fax: 301-480-9917;
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7
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Kaur D, Khaniya U, Zhang Y, Gunner MR. Protein Motifs for Proton Transfers That Build the Transmembrane Proton Gradient. Front Chem 2021; 9:660954. [PMID: 34211960 PMCID: PMC8239185 DOI: 10.3389/fchem.2021.660954] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/31/2021] [Indexed: 11/13/2022] Open
Abstract
Biological membranes are barriers to polar molecules, so membrane embedded proteins control the transfers between cellular compartments. Protein controlled transport moves substrates and activates cellular signaling cascades. In addition, the electrochemical gradient across mitochondrial, bacterial and chloroplast membranes, is a key source of stored cellular energy. This is generated by electron, proton and ion transfers through proteins. The gradient is used to fuel ATP synthesis and to drive active transport. Here the mechanisms by which protons move into the buried active sites of Photosystem II (PSII), bacterial RCs (bRCs) and through the proton pumps, Bacteriorhodopsin (bR), Complex I and Cytochrome c oxidase (CcO), are reviewed. These proteins all use water filled proton transfer paths. The proton pumps, that move protons uphill from low to high concentration compartments, also utilize Proton Loading Sites (PLS), that transiently load and unload protons and gates, which block backflow of protons. PLS and gates should be synchronized so PLS proton affinity is high when the gate opens to the side with few protons and low when the path is open to the high concentration side. Proton transfer paths in the proteins we describe have different design features. Linear paths are seen with a unique entry and exit and a relatively straight path between them. Alternatively, paths can be complex with a tangle of possible routes. Likewise, PLS can be a single residue that changes protonation state or a cluster of residues with multiple charge and tautomer states.
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Affiliation(s)
- Divya Kaur
- Department of Chemistry, The Graduate Center, City University of New York, New York, NY, United States.,Department of Physics, City College of New York, New York, NY, United States
| | - Umesh Khaniya
- Department of Physics, City College of New York, New York, NY, United States.,Department of Physics, The Graduate Center, City University of New York, New York, NY, United States
| | - Yingying Zhang
- Department of Physics, City College of New York, New York, NY, United States.,Department of Physics, The Graduate Center, City University of New York, New York, NY, United States
| | - M R Gunner
- Department of Chemistry, The Graduate Center, City University of New York, New York, NY, United States.,Department of Physics, City College of New York, New York, NY, United States.,Department of Physics, The Graduate Center, City University of New York, New York, NY, United States
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8
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Rashed AA, Ahmad H, Abdul Khalid SK, Rathi DNG. The Potential Use of Sialic Acid From Edible Bird's Nest to Attenuate Mitochondrial Dysfunction by In Vitro Study. Front Pharmacol 2021; 12:633303. [PMID: 33912049 PMCID: PMC8072155 DOI: 10.3389/fphar.2021.633303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/22/2021] [Indexed: 01/03/2023] Open
Abstract
Edible bird's nest (EBN) is one of the expensive functional foods in herbal medicine. One of the major glyconutrients in EBN is sialic acid, which has a beneficial effect on neurological and intellectual capability in mammals. The aims of this research were to study the effects of sialic acid from EBN on cell viability and to determine its effect on mitochondria membrane potential (MtMP) in Caco-2, SK-N-MC, SH-SY5Y, and PC-12 cell lines. Fourteen samples of raw EBN were collected from four different states in Malaysia. The confluency of the epithelial monolayers measurement of the tight junction for all the cell lines was determined using transepithelial electrical resistance (TEER), and the sialic acid uptake study in cell lines was determined by using ultra-high performance liquid chromatography (UHPLC). The MTT assay was conducted for cell viability study. The MtMP in cell lines was determined using the Mito Probe JC-1 Assay by flow cytometer analysis. We have recorded a statistically significant difference between the uptake of sialic acid from EBN and the standard solution. A higher amount of sialic acid was absorbed by the cells from extract of EBN compared to the standard solution. The amounts of sialic acid uptake in Caco-2, SK-N-MC, SH-SY5Y, and PC-12 cell lines were (0.019 ± 0.001), (0.034 ± 0.006), (0.021 ± 0.002), and (0.025 ± 0.000) µmol/L, respectively. The MTT results indicated that the concentration of sialic acid increased the cell viability and showed no cytotoxicity effects on cell lines when they were exposed to the sialic acid extract and sialic acid standard at all the tested concentrations. The number of active mitochondria was found to be significantly higher in SH-SY5Y cell lines with a 195% increase when treated with sialic acid from EBN. Although many researchers around the globe use SH-SY5Y and SK-N-MC for Alzheimer's disease (AD) study, based on our finding, SH-SY5Y was found to be the most suitable cell line for AD study by in vitro works where it has a known relationship with mitochondrial dysfunction.
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Affiliation(s)
- Aswir Abd Rashed
- Nutrition, Metabolism and Cardiovascular Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health, Shah Alam, Malaysia
| | - Hafandi Ahmad
- Departments of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, Serdang, Malaysia
| | - Siti Khadijah Abdul Khalid
- Nutrition, Metabolism and Cardiovascular Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health, Shah Alam, Malaysia
| | - Devi-Nair Gunasegavan Rathi
- Nutrition, Metabolism and Cardiovascular Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health, Shah Alam, Malaysia
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9
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Gueguen N, Lenaers G, Reynier P, Weissig V, Edeas M. Mitochondrial Dysfunction in Mitochondrial Medicine: Current Limitations, Pitfalls, and Tomorrow. Methods Mol Biol 2021; 2276:1-29. [PMID: 34060029 DOI: 10.1007/978-1-0716-1266-8_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Until recently restricted to hereditary mitochondrial diseases, mitochondrial dysfunction is now recognized as a key player and strategic factor in the pathophysiological of many human diseases, ranging from the metabolism, vascular, cardiac, and neurodegenerative diseases to cancer. Because of their participation in a myriad of cellular functions and signaling pathways, precisely identifying the cause of mitochondrial "dysfunctions" can be challenging and requires robust and controlled techniques. Initially limited to the analysis of the respiratory chain functioning, these analytical techniques now enlarge to the analyses of mitochondrial and cellular metabolism, based on metabolomic approaches.Here, we address the methods used to assay mitochondrial dysfunction, with a highlight on the techniques used in diagnosis on tissues and cells derived from patients, the information they provide, and their strength and weakness.Targeting mitochondrial dysfunction by various strategies is a huge challenge, requires robust methods of evaluation, and should be able to take into consideration the mitochondria dynamics and localization. The future of mitochondrial medicine is strongly related to a perfect comprehension of its dysfunction.
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Affiliation(s)
- Naig Gueguen
- UMR CNRS 6015-INSERM U1083, MitoVasc Institute, University of Angers, Angers, France.,Department of Biochemistry and Genetics, University Hospital of Angers, Angers, France
| | - Guy Lenaers
- UMR CNRS 6015-INSERM U1083, MitoVasc Institute, University of Angers, Angers, France
| | - Pascal Reynier
- UMR CNRS 6015-INSERM U1083, MitoVasc Institute, University of Angers, Angers, France.,Department of Biochemistry and Genetics, University Hospital of Angers, Angers, France
| | - Volkmar Weissig
- Department of Pharmaceutical Sciences and Nanocenter of Excellence, Midwestern University College of Pharmacy at Glendale, Glendale, AZ, USA
| | - Marvin Edeas
- Université de Paris, INSERM U1016, Institut Cochin, CNRS UMR8104, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
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10
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Walker BJ, Kramer DM, Fisher N, Fu X. Flexibility in the Energy Balancing Network of Photosynthesis Enables Safe Operation under Changing Environmental Conditions. PLANTS (BASEL, SWITZERLAND) 2020; 9:E301. [PMID: 32121540 PMCID: PMC7154899 DOI: 10.3390/plants9030301] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/13/2020] [Accepted: 02/15/2020] [Indexed: 12/11/2022]
Abstract
Given their ability to harness chemical energy from the sun and generate the organic compounds necessary for life, photosynthetic organisms have the unique capacity to act simultaneously as their own power and manufacturing plant. This dual capacity presents many unique challenges, chiefly that energy supply must be perfectly balanced with energy demand to prevent photodamage and allow for optimal growth. From this perspective, we discuss the energy balancing network using recent studies and a quantitative framework for calculating metabolic ATP and NAD(P)H demand using measured leaf gas exchange and assumptions of metabolic demand. We focus on exploring how the energy balancing network itself is structured to allow safe and flexible energy supply. We discuss when the energy balancing network appears to operate optimally and when it favors high capacity instead. We also present the hypothesis that the energy balancing network itself can adapt over longer time scales to a given metabolic demand and how metabolism itself may participate in this energy balancing.
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Affiliation(s)
- Berkley J. Walker
- Plant Research Laboratory, Michigan State University, East Lansing, MI 48823, USA; (D.M.K.); (N.F.); (X.F.)
- Department of Plant Biology, Michigan State University, East Lansing, MI 48823, USA
| | - David M. Kramer
- Plant Research Laboratory, Michigan State University, East Lansing, MI 48823, USA; (D.M.K.); (N.F.); (X.F.)
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48823, USA
| | - Nicholas Fisher
- Plant Research Laboratory, Michigan State University, East Lansing, MI 48823, USA; (D.M.K.); (N.F.); (X.F.)
| | - Xinyu Fu
- Plant Research Laboratory, Michigan State University, East Lansing, MI 48823, USA; (D.M.K.); (N.F.); (X.F.)
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11
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Islam MT, Mishra SK, Tripathi S, de Alencar MVOB, e Sousa JMDC, Rolim HML, de Medeiros MDGF, Ferreira PMP, Rouf R, Uddin SJ, Mubarak MS, Melo-Cavalcante AADC. Mycotoxin-assisted mitochondrial dysfunction and cytotoxicity: Unexploited tools against proliferative disorders. IUBMB Life 2018; 70:1084-1092. [DOI: 10.1002/iub.1932] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 05/30/2018] [Accepted: 07/26/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Muhammad Torequl Islam
- Department for Management of Science and Technology Development; Ton Duc Thang University; Ho Chi Minh City 700000 Vietnam
- Faculty of Pharmacy; Ton Duc Thang University; Ho Chi Minh City 700000 Vietnam
| | - Siddhartha Kumar Mishra
- Cancer Biology Laboratory; School of Biological Sciences (Zoology), Dr. Harisingh Gour Central University; Sagar 470003 Madhya Pradesh India
| | - Swati Tripathi
- Amity Institute of Microbial Technology; Amity University; Noida 201313 Uttar Pradesh India
| | | | - João Marcelo de Castro e Sousa
- Postgraduate Program in Pharmaceutical Sciences; Federal University of Piaui; Teresina 64 049-550 Brazil
- Department of Biological Sciences; Federal University of Piauí; Picos Piauí 64 067-670 Brazil
| | - Hercília Maria Lins Rolim
- Postgraduate Program in Pharmaceutical Sciences; Federal University of Piaui; Teresina 64 049-550 Brazil
| | - Maria das Graças Freire de Medeiros
- Department for Management of Science and Technology Development; Ton Duc Thang University; Ho Chi Minh City 700000 Vietnam
- Department of Biological Sciences; Federal University of Piauí; Picos Piauí 64 067-670 Brazil
| | - Paulo Michel Pinheiro Ferreira
- Postgraduate Program in Pharmaceutical Sciences; Federal University of Piaui; Teresina 64 049-550 Brazil
- Department of Biophysics and Physiology; Laboratory of Experimental Cancerology, Federal University of Piauí; Teresina Piauí 64 049-550 Brazil
| | - Razina Rouf
- Department of Pharmacy; Bangabandhu Sheikh Mujibur Rahman Science & Technology University; Gopalganj Bangladesh
| | - Shaikh Jamal Uddin
- Pharmacy Discipline; Life Science School, Khulna University; Khulna Bangladesh
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12
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Ribeiro JA, Benfeito S, Cagide F, Teixeira J, Oliveira PJ, Borges F, Silva AF, Pereira CM. Electrochemical Behavior of a Mitochondria-Targeted Antioxidant at an Interface between Two Immiscible Electrolyte Solutions: An Alternative Approach to Study Lipophilicity. Anal Chem 2018; 90:7989-7996. [DOI: 10.1021/acs.analchem.8b00787] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- José A. Ribeiro
- Research Center
in Chemistry (CIQUP), Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal
| | - Sofia Benfeito
- Research Center
in Chemistry (CIQUP), Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal
| | - Fernando Cagide
- Research Center
in Chemistry (CIQUP), Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal
| | - José Teixeira
- Research Center
in Chemistry (CIQUP), Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal
- Center for Neuroscience and Cell Biology, University of Coimbra, UC-Biotech Building, Biocant Park, Cantanhede 3060-197, Portugal
| | - Paulo J. Oliveira
- Center for Neuroscience and Cell Biology, University of Coimbra, UC-Biotech Building, Biocant Park, Cantanhede 3060-197, Portugal
| | - Fernanda Borges
- Research Center
in Chemistry (CIQUP), Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal
| | - António F. Silva
- Research Center
in Chemistry (CIQUP), Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal
| | - Carlos M. Pereira
- Research Center
in Chemistry (CIQUP), Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal
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Kalem MC, Gerasimov ES, Vu PK, Zimmer SL. Gene expression to mitochondrial metabolism: Variability among cultured Trypanosoma cruzi strains. PLoS One 2018; 13:e0197983. [PMID: 29847594 PMCID: PMC5976161 DOI: 10.1371/journal.pone.0197983] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 05/11/2018] [Indexed: 11/18/2022] Open
Abstract
The insect-transmitted protozoan parasite Trypanosoma cruzi experiences changes in nutrient availability and rate of flux through different metabolic pathways across its life cycle. The species encompasses much genetic diversity of both the nuclear and mitochondrial genomes among isolated strains. The genetic or expression variation of both genomes are likely to impact metabolic responses to environmental stimuli, and even steady state metabolic function, among strains. To begin formal characterization these differences, we compared aspects of metabolism between genetically similar strains CL Brener and Tulahuen with less similar Esmeraldo and Sylvio X10 strains in a culture environment. Epimastigotes of all strains took up glucose at similar rates. However, the degree of medium acidification that could be observed when glucose was absent from the medium varied by strain, indicating potential differences in excreted metabolic byproducts. Our main focus was differences related to electron transport chain function. We observed differences in ATP-coupled respiration and maximal respiratory capacity, mitochondrial membrane potential, and mitochondrial morphology between strains, despite the fact that abundances of two nuclear-encoded proteins of the electron transport chain are similar between strains. RNA sequencing reveals strain-specific differences in abundances of mRNAs encoding proteins of the respiratory chain but also other metabolic processes. From these differences in metabolism and mitochondrial phenotypes we have generated tentative models for the differential metabolic fluxes or differences in gene expression that may underlie these results.
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Affiliation(s)
- Murat C. Kalem
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota, United States of America
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth campus, Duluth, Minnesota, United States of America
| | | | - Pamela K. Vu
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota, United States of America
| | - Sara L. Zimmer
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth campus, Duluth, Minnesota, United States of America
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14
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Gunner MR, Koder R. The design features cells use to build their transmembrane proton gradient. Phys Biol 2017; 14:013001. [DOI: 10.1088/1478-3975/14/1/013001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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15
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UCPs, at the interface between bioenergetics and metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2443-56. [PMID: 27091404 DOI: 10.1016/j.bbamcr.2016.04.013] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 01/25/2023]
Abstract
The first member of the uncoupling protein (UCP) family, brown adipose tissue uncoupling protein 1 (UCP1), was identified in 1976. Twenty years later, two closely related proteins, UCP2 and UCP3, were described in mammals. Homologs of these proteins exist in other organisms, including plants. Uncoupling refers to a deterioration of energy conservation between substrate oxidation and ADP phosphorylation. Complete energy conservation loss would be fatal but fine-tuning can be beneficial for processes such as thermogenesis, redox control, and prevention of mitochondrial ROS release. The coupled/uncoupled state of mitochondria is related to the permeability of the inner membrane and the proton transport mediated by activated UCPs underlies the uncoupling activity of these proteins. Proton transport by UCP1 is activated by fatty acids and this ensures thermogenesis. In vivo in absence of this activation UCP1 remains inhibited with no transport activity. A similar situation now seems unlikely for UCP2 and UCP3 and while activation of their proton transport has been described its physiological relevance remains uncertain and their influence can be envisaged as a result of another transport pathway that takes place in the absence of activation. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
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16
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Transport of pyruvate into mitochondria is involved in methylmercury toxicity. Sci Rep 2016; 6:21528. [PMID: 26899208 PMCID: PMC4761912 DOI: 10.1038/srep21528] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 01/26/2016] [Indexed: 01/24/2023] Open
Abstract
We have previously demonstrated that the overexpression of enzymes involved in the production of pyruvate, enolase 2 (Eno2) and D-lactate dehydrogenase (Dld3) renders yeast highly sensitive to methylmercury and that the promotion of intracellular pyruvate synthesis may be involved in intensifying the toxicity of methylmercury. In the present study, we showed that the addition of pyruvate to culture media in non-toxic concentrations significantly enhanced the sensitivity of yeast and human neuroblastoma cells to methylmercury. The results also suggested that methylmercury promoted the transport of pyruvate into mitochondria and that the increased pyruvate concentrations in mitochondria were involved in intensifying the toxicity of methylmercury without pyruvate being converted to acetyl-CoA. Furthermore, in human neuroblastoma cells, methylmercury treatment alone decreased the mitochondrial membrane potential, and the addition of pyruvate led to a further significant decrease. In addition, treatment with N-acetylcysteine (an antioxidant) significantly alleviated the toxicity of methylmercury and significantly inhibited the intensification of methylmercury toxicity by pyruvate. Based on these data, we hypothesize that methylmercury exerts its toxicity by raising the level of pyruvate in mitochondria and that mitochondrial dysfunction and increased levels of reactive oxygen species are involved in the action of pyruvate.
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17
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Mailloux RJ. Teaching the fundamentals of electron transfer reactions in mitochondria and the production and detection of reactive oxygen species. Redox Biol 2015; 4:381-98. [PMID: 25744690 PMCID: PMC4348434 DOI: 10.1016/j.redox.2015.02.001] [Citation(s) in RCA: 184] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 02/01/2015] [Indexed: 12/11/2022] Open
Abstract
Mitochondria fulfill a number of biological functions which inherently depend on ATP and O2(-•)/H2O2 production. Both ATP and O2(-•)/H2O2 are generated by electron transfer reactions. ATP is the product of oxidative phosphorylation whereas O2(-•) is generated by singlet electron reduction of di-oxygen (O2). O2(-•) is then rapidly dismutated by superoxide dismutase (SOD) producing H2O2. O2(-•)/H2O2 were once viewed as unfortunately by-products of aerobic respiration. This characterization is fitting considering over production of O2(-•)/H2O2 by mitochondria is associated with range of pathological conditions and aging. However, O2(-•)/H2O2 are only dangerous in large quantities. If produced in a controlled fashion and maintained at a low concentration, cells can benefit greatly from the redox properties of O2(-•)/H2O2. Indeed, low rates of O2(-•)/H2O2 production are required for intrinsic mitochondrial signaling (e.g. modulation of mitochondrial processes) and communication with the rest of the cell. O2(-•)/H2O2 levels are kept in check by anti-oxidant defense systems that sequester O2(-•)/H2O2 with extreme efficiency. Given the importance of O2(-•)/H2O2 in cellular function, it is imperative to consider how mitochondria produce O2(-•)/H2O2 and how O2(-•)/H2O2 genesis is regulated in conjunction with fluctuations in nutritional and redox states. Here, I discuss the fundamentals of electron transfer reactions in mitochondria and emerging knowledge on the 11 potential sources of mitochondrial O2(-•)/H2O2 in tandem with their significance in contributing to overall O2(-•)/H2O2 emission in health and disease. The potential for classifying these different sites in isopotential groups, which is essentially defined by the redox properties of electron donator involved in O2(-•)/H2O2 production, as originally suggested by Brand and colleagues is also surveyed in detail. In addition, redox signaling mechanisms that control O2(-•)/H2O2 genesis from these sites are discussed. Finally, the current methodologies utilized for measuring O2(-•)/H2O2 in isolated mitochondria, cell culture and in vivo are reviewed.
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Affiliation(s)
- Ryan J Mailloux
- Department of Biology, Faculty of Sciences, University of Ottawa, 30 Marie Curie, Ottawa, ON, Canada K1N 6N5.
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18
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Oxidative Stress-Induced Signaling Pathways Implicated in the Pathogenesis of Parkinson’s Disease. Neuromolecular Med 2014; 16:217-30. [DOI: 10.1007/s12017-014-8294-x] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 02/03/2014] [Indexed: 01/05/2023]
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Gunner MR, Amin M, Zhu X, Lu J. Molecular mechanisms for generating transmembrane proton gradients. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1827:892-913. [PMID: 23507617 PMCID: PMC3714358 DOI: 10.1016/j.bbabio.2013.03.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/28/2013] [Accepted: 03/01/2013] [Indexed: 01/02/2023]
Abstract
Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side.
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Affiliation(s)
- M R Gunner
- Department of Physics, City College of New York, New York, NY 10031, USA.
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20
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Function and characteristics of PINK1 in mitochondria. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2013; 2013:601587. [PMID: 23533695 PMCID: PMC3600171 DOI: 10.1155/2013/601587] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 02/02/2013] [Accepted: 02/04/2013] [Indexed: 11/24/2022]
Abstract
Mutations in phosphatase and tensin homologue-induced kinase 1 (PINK1) cause recessively inherited Parkinson's disease, a neurodegenerative disorder linked to mitochondrial dysfunction. Studies support the notion of neuroprotective roles for the PINK1, as it protects cells from damage-mediated mitochondrial dysfunction, oxidative stress, and cell apoptosis. PARL is a mitochondrial resident rhomboid serine protease, and it has been reported to mediate the cleavage of the PINK1. Interestingly, impaired mitophagy, an important autophagic quality control mechanism that clears the cells of damaged mitochondria, may also be an underlying mechanism of disease pathogenesis in patients for Parkinson's disease with the PARL mutations. Functional studies have revealed that PINK1 recruits Parkin to mitochondria to initiate the mitophagy. PINK1 is posttranslationally processed, whose level is definitely regulated in healthy steady state of mitochondria. As a consequence, PINK1 plays a pivotal role in mitochondrial healthy homeostasis.
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21
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Catalina-Rodriguez O, Kolukula VK, Tomita Y, Preet A, Palmieri F, Wellstein A, Byers S, Giaccia AJ, Glasgow E, Albanese C, Avantaggiati ML. The mitochondrial citrate transporter, CIC, is essential for mitochondrial homeostasis. Oncotarget 2012; 3:1220-35. [PMID: 23100451 PMCID: PMC3717962 DOI: 10.18632/oncotarget.714] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 10/18/2012] [Indexed: 12/25/2022] Open
Abstract
Dysregulation of the pathways that preserve mitochondrial integrity hallmarks many human diseases including diabetes, neurodegeration, aging and cancer. The mitochondrial citrate transporter gene, SLC25A1 or CIC, maps on chromosome 22q11.21, a region amplified in some tumors and deleted in developmental disorders known as velo-cardio-facial- and DiGeorge syndromes. We report here that in tumor cells CIC maintains mitochondrial integrity and bioenergetics, protects from mitochondrial damage and circumvents mitochondrial depletion via autophagy, hence promoting proliferation. CIC levels are increased in human cancers and its inhibition has anti-tumor activity, albeit with no toxicity on adult normal tissues. The knock-down of the CIC gene in zebrafish leads to mitochondria depletion and to proliferation defects that recapitulate features of human velo-cardio-facial syndrome, a phenotype rescued by blocking autophagy. Our findings reveal that CIC maintains mitochondrial homeostasis in metabolically active, high proliferating tissues and imply that this protein is a therapeutic target in cancer and likely, in other human diseases.
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Affiliation(s)
- Olga Catalina-Rodriguez
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Vamsi K. Kolukula
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - York Tomita
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Anju Preet
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | | | - Anton Wellstein
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Stephen Byers
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Amato J. Giaccia
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA
| | - Eric Glasgow
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Chris Albanese
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Maria Laura Avantaggiati
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
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22
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Verkhovskaya M, Bloch DA. Energy-converting respiratory Complex I: on the way to the molecular mechanism of the proton pump. Int J Biochem Cell Biol 2012; 45:491-511. [PMID: 22982742 DOI: 10.1016/j.biocel.2012.08.024] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 08/27/2012] [Accepted: 08/28/2012] [Indexed: 12/16/2022]
Abstract
In respiring organisms the major energy transduction flux employs the transmembrane electrochemical proton gradient as a physical link between exergonic redox reactions and endergonic ADP phosphorylation. Establishing the gradient involves electrogenic, transmembrane H(+) translocation by the membrane-embedded respiratory complexes. Among others, Complex I (NADH:ubiquinone oxidoreductase) is the most structurally complex and functionally enigmatic respiratory enzyme; its molecular mechanism is as yet unknown. Here we highlight recent progress and discuss the catalytic events during Complex I turnover in relation to their role in energy conversion and to the enzyme structure.
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Affiliation(s)
- Marina Verkhovskaya
- Helsinki Bioenergetics Group, Institute of Biotechnology, PO Box 65 (Viikinkaari 1) FIN-00014 University of Helsinki, Finland.
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23
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Abstract
Potential roles for lactate in the energetics of brain activation have changed radically during the past three decades, shifting from waste product to supplemental fuel and signaling molecule. Current models for lactate transport and metabolism involving cellular responses to excitatory neurotransmission are highly debated, owing, in part, to discordant results obtained in different experimental systems and conditions. Major conclusions drawn from tabular data summarizing results obtained in many laboratories are as follows: Glutamate-stimulated glycolysis is not an inherent property of all astrocyte cultures. Synaptosomes from the adult brain and many preparations of cultured neurons have high capacities to increase glucose transport, glycolysis, and glucose-supported respiration, and pathway rates are stimulated by glutamate and compounds that enhance metabolic demand. Lactate accumulation in activated tissue is a minor fraction of glucose metabolized and does not reflect pathway fluxes. Brain activation in subjects with low plasma lactate causes outward, brain-to-blood lactate gradients, and lactate is quickly released in substantial amounts. Lactate utilization by the adult brain increases during lactate infusions and strenuous exercise that markedly increase blood lactate levels. Lactate can be an 'opportunistic', glucose-sparing substrate when present in high amounts, but most evidence supports glucose as the major fuel for normal, activated brain.
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Abstract
Background LEA (late embryogenesis abundant) proteins encode conserved N-terminal mitochondrial signal domains and C-terminal (A/TAEKAK) motif repeats, long-presumed to confer cell resistance to stress and death cues. This prompted the hypothesis that LEA proteins are central to mitochondria mechanisms that connect bioenergetics with cell responses to stress and death signaling. In support of this hypothesis, recent studies have demonstrated that mammalian LEA protein PRELI can act as a biochemical hub, which upholds mitochondria energy metabolism, while concomitantly promoting B cell resistance to stress and induced death. Hence, it is important to define in vivo the physiological relevance of PRELI expression. Methods and Findings Given the ubiquitous PRELI expression during mouse development, embryo lethality could be anticipated. Thus, conditional gene targeting was engineered by insertion of flanking loxP (flox)/Cre recognition sites on PRELI chromosome 13 (Chr 13) locus to abort its expression in a tissue-specific manner. After obtaining mouse lines with homozygous PRELI floxed alleles (PRELIf/f), the animals were crossed with CD19-driven Cre-recombinase transgenic mice to investigate whether PRELI inactivation could affect B-lymphocyte physiology and survival. Mice with homozygous B cell-specific PRELI deletion (CD19-Cre/Chr13 PRELI−/−) bred normally and did not show any signs of morbidity. Histopathology and flow cytometry analyses revealed that cell lineage identity, morphology, and viability were indistinguishable between wild type CD19-Cre/Chr13 PRELI+/+ and CD19-Cre/Chr13 PRELI−/− deficient mice. Furthermore, B cell PRELI gene expression seemed unaffected by Chr13 PRELI gene targeting. However, identification of additional PRELI loci in mouse Chr1 and Chr5 provided an explanation for the paradox between LEA-dependent cytoprotection and the seemingly futile consequences of Chr 13 PRELI gene inactivation. Importantly, PRELI expression from spare gene loci appeared ample to surmount Chr 13 PRELI gene deficiency. Conclusions These findings suggest that PRELI is a vital LEA B cell protein with failsafe genetics.
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25
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Compton S, Kim C, Griner NB, Potluri P, Scheffler IE, Sen S, Jerry DJ, Schneider S, Yadava N. Mitochondrial dysfunction impairs tumor suppressor p53 expression/function. J Biol Chem 2011; 286:20297-312. [PMID: 21502317 DOI: 10.1074/jbc.m110.163063] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recently, mitochondria have been suggested to act in tumor suppression. However, the underlying mechanisms by which mitochondria suppress tumorigenesis are far from being clear. In this study, we have investigated the link between mitochondrial dysfunction and the tumor suppressor protein p53 using a set of respiration-deficient (Res(-)) mammalian cell mutants with impaired assembly of the oxidative phosphorylation machinery. Our data suggest that normal mitochondrial function is required for γ-irradiation (γIR)-induced cell death, which is mainly a p53-dependent process. The Res(-) cells are protected against γIR-induced cell death due to impaired p53 expression/function. We find that the loss of complex I biogenesis in the absence of the MWFE subunit reduces the steady-state level of the p53 protein, although there is no effect on the p53 protein level in the absence of the ESSS subunit that is also essential for complex I assembly. The p53 protein level was also reduced to undetectable levels in Res(-) cells with severely impaired mitochondrial protein synthesis. This suggests that p53 protein expression is differentially regulated depending upon the type of electron transport chain/respiratory chain deficiency. Moreover, irrespective of the differences in the p53 protein expression profile, γIR-induced p53 activity is compromised in all Res(-) cells. Using two different conditional systems for complex I assembly, we also show that the effect of mitochondrial dysfunction on p53 expression/function is a reversible phenomenon. We believe that these findings will have major implications in the understanding of cancer development and therapy.
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Affiliation(s)
- Shannon Compton
- Pioneer Valley Life Sciences Institute, Springfield, Massachusetts 01107, USA
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